Antenna interaction compensating means



Aug. 24; 1'943.A A. G. KANDolAN 2,327,435

ANTENNA 'INTERACTION COMFENSATING MEANS Filed OC 25, 1941 FIG. 1.

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Patented Aug. 24, 1943 ANTENNA INTERACTION COMPENSATING MEANS Armig G. Kandoian, New York, N. Y., assignor to Federal Telephone & Radio Corporation, a corporation of Delaware Application October 23, 1941, Serial No. 416,163

4 Claims.

This invention relates to method and means for compensating interaction between antenna elements and more particularly to a-n arrangement for compensating interaction .between antenna elements of a radio beacon.

A radio beacon with quadrant identification has been proposed in which two separate radio beacon arrays are arranged at right angles to one another, the beacons each consisting of several units. In this proposed system two of the antenna units are arranged directly in vertical alignment. A means was proposed in this system for compensating somewhat the interaction between these vertically arranged units. It has been found, however, that with this arrangement interference occurred at high altitudes within the angle of about 90 subtended directly above the beacon, dueto uncompensated minor lobes.

It is a principal object of' my invention to provide a method and means for Acompensating precisely the reaction between two closely related antenna elements so as to avoid interference due to minor lobes at any angle. Y

According to a vfeature of my invention com'- pensation for interaction is attained by feeding energy from one 'of the antennae of the system to the interfering antenna unit and to position the'feed line interconnecting the antennae and control the phase of energy conducted over the feed line to substantially completely neutralize all parasitic effects.' j f A better understanding of "myV invention and the objects and features thereof' will be' had from the particular description of a preferred embodiment thereof made with referen'ceto thej accompanying drawinain'which Fi-g. 1 is a 'schematic 'diagram of 'a preferred embodiment of' the radio beacon incorporating the features'of my invention;

Fig. 2 is'afdiagrammatic illustration of radiai tion diagram produced by such a radio beacon.

In Fig'. 1 is shown avradio range beacon comprising antennaeZ, 3 and i to which energy is supplied f rom transmitter I over modulators Ip and I I,'"a. nd network'lg. -Central antenna unit 3 is supplied over the'flin'e 'II connected tofnret- Work I2. The energy thus'supplied to these an# tenna units willproduce a field pattern such as shown at 2%', Fig.' it. at right antics to the :beacon comprising antennae 2, 3 and 4 is provided a further beacon arrangement consisting of antennae 2A, 3A and 4A. Energy from source I and from a tone source I5 is fed to modulator I4 which is preferably a balanced modulator and from I4 energy is supplied to a keying reversing (Cl. Z50-11) switch I6 to the two side radiators 2A and 4A. Another portion of the energy from modulator I4 is fed over line I'IA to antenna unit 3A. This energy supplied to the auxiliary or identification beacon contains only side bands which may be lreceived on an aircraft with the carrier frequency transmitted from antenna 3.

Antenna units 2 and 4 are connected in a manner to prevent parasitic effects due to energy from antennae 3 and 3A. Similarly antenna units 2A and 4A are arranged to prevent parasitic effects due to energy from antennae 3A and 3. This arrangement then prevents any parasitic action of the side radiators 2, 4, 2A or 4A, because of any radiation effects at 3 or 3A. There remains, however, a certain amount of interaction between units 3 and 3A.

In a proposed arrangement this parasitic action was partiallycompensated by feeding energy between lines I`I and I'IA. The adjustment for this purpose was achieved by moving one connection point of a line interconnecting lines II and IIA along conductors Il or IIA until no interaction eiect was noticed between lines I'I and IIA. It was found, however, that at high altitudes there were troublesome multiple lobes or cross-over effects due to interaction between antennae 3 and 3A.

The proper points of connection for a feed line to. compensate or neutralize completely parasitio eiects both Ibetween I'I and IlA Vas well as between 3 and 3A should be madeat a point electrically equal to a half-Wave length of the operating frequency from each of the antenna units. These ponts'may be most readily checked by the following method. Antenna 3 may be energized while line I'IA is completely disconnected from any energizingsource. A short circuiting` bar is then moved along line I'IA until a poi-nt is reached at which the induced current in antenna 3A reduces to zero. A similar test is thenmade of line I'I by energizing antenna 3A and .disconnecting line I'I from any source of supply. If, then, an interconnection is made between lines Il and IIA at the points where the induced currents reduce to zero andthe phase and amplitude of the energy fed between theselines is properly adjusted, a complete compensation will takeV .place and no inthe wfl then occur.

In order to provide a readily adjustable interconnection, preferably, short circuited quarter wavelength transmission line sections I8, IBA are bridged across lines I'I, I'IA, respectively. At chosen points on sections I8, IBA is connected line I9I preferably provided with one or more 

